N-type aluminum nitride single-crystal substrate and vertical nitride semiconductor device

Abstract

A vertical nitride semiconductor device includes an n-type aluminum nitride single-crystal substrate having an Si content of 3×10 17 to 1×10 20 cm −3 and a dislocation density of 10 6 cm −2 or less. An ohmic electrode layer is formed on an N-polarity side of the n-type aluminum nitride single-crystal substrate.

The invention claimed is: 
     
       1. A laminated body stacked with a layer represented by AI x Ga 1-x N, wherein X is a rational number satisfying 0.3≦X≦0.8 and having a Si content of 1×10 18  to 5×10 19  cm −3 , on at least one principal plane of an n-type aluminum nitride single crystal substrate, wherein said n-type aluminum nitride single crystal substrate has an Si content of 3×10 17  to 1×10 20  cm −3 , a dislocation density of 10 6  cm −2  or less, and a thickness of 50 to 500 μm. 
     
     
       2. A vertical nitride semiconductor device comprising electrode layers on top and bottom of principal planes of the layered body as set forth in  claim 1 . 
     
     
       3. The vertical nitride semiconductor device as set forth in  claim 2  wherein one electrode layer on the layer represented by Al X Ga 1-X N, wherein X is a rational number satisfying 0.3≦X≦0.8 is an ohmic electrode layer. 
     
     
       4. A vertical Schottky barrier diode wherein one electrode layer on the n-type aluminum nitride single crystal substrate in the vertical nitride semiconductor device as set forth in  claim 3  is a Schottky electrode layer. 
     
     
       5. The vertical Schottky barrier diode as set forth in  claim 4  wherein an electric current density is 10 −6  Acm −2  or less when a reverse voltage is 100V. 
     
     
       6. The laminated body of  claim 1  wherein the dislocation density of the n-type aluminum nitride single crystal substrate is 10 2  cm −2  to 10 4  cm −2 . 
     
     
       7. The laminated body of  claim 1  wherein the Si content of the n-type aluminum nitride single crystal substrate is 5×10 19  to 1×10 20  cm −3 . 
     
     
       8. A vertical nitride semiconductor device comprising:
 the laminated body as set forth in  claim 1 ; 
 an ohmic electrode layer comprising Ti or Al on the layer represented by Al X Ga 1-X N wherein X is a rational number satisfying 0.3≦X≦0.8; and 
 a Schottky electrode layer comprising Ni, Pt, or Pd on the principal plane side of said n-type aluminum nitride single crystal substrate.